Tag Archives: Caribbean Reef Fish

CHERUBFISH (PYGMY ANGELFISH): BAHAMAS REEF FISH (23)

Time for a bright little denizen of the not-so-deep. The Cherubfish Centropyge argi or pygmy angelfish is a very small (8cm) and distinctively coloured angelfish species. These fish are native to the Caribbean and Gulf of Mexico, and flicker round the coral reefs happily feeding as they go (see the video below to see how busily they forage). Or maybe they are just having a good time…

The Cherubfish is unsurprisingly a popular aquarium species. Don’t rush straight out and buy some though: a typical warning says “like other angel fish, they are not completely 100% reef-safe. Results vary among individual fish and tank qualities (size, feeding, tankmates, etc.), so caution is recommended when adding this fish to a coral tank“. You can read the whys and the wherefores HERE – sadly I lack the vibrant interest in aquaria to go into it myself…

Looking beyond Melinda’s lovely images of the species, I have found that these creatures will often show more yellow at the nose end. Here’s an example of a more two-tone Cherubfish in case you come across one.

I mentioned that Cherubfish flicker around the reefs instead of proceeding serenely and in an orderly fashion. Have a look at this short video to see what active little fish they are.

PEACOCK FLOUNDER: BAHAMAS REEF FISH (21)

PEACOCK FLOUNDER or PLATE FISH Bothus lunatus

I have briefly featured this fish before in the context of its extraordinary camouflage abilities; and also its interesting ocular arrangements. Time to give it another swim around, I think, with some additional photos that I have collected.

Bothus lunatus is the Atlantic / Caribbean version of a species also found in the Pacific and Indian oceans. Adults may grow up to 18 inches long. The species is a ‘lefteye’ flounder, with both eyes on its left (top) side & its right side underneath. However a baby flounder looks & swims like normal fish, with bilateral eyes. As it grows, the right eye gradually ‘moves’ round to the topside, and it becomes a flatfish.

A flounder’s eyes can move independently of each other. One may look forwards, the other backwards

‘NOW YOU SEE IT…’ CAMO-FISH

The Peacock Flounder has extraordinary colour-changing powers, and can rapidly vary its background colour to make it closely resemble that of its surroundings. This enables it camouflage itself as it lies on the seabed.It can change coloration completely in between two to eight seconds.

Four frames of the same fish taken a few minutes apart showing the ability of flounders to change colors to match the surroundings (Wiki)

Check out these imitative patterns in Bahamas waters…

There are two advantages to the ability to camouflage (‘cryptic coloration‘). One is obviously to avoid detection by predators. The other is to enable the flounder to ambush its meals. They feed primarily on small fishes, crabs and shrimps, lying concealed on the seabed and grabbing any unwary prey that ventures too close. They will even partially bury themselves in the sand, leaving just their eye-stalks keeping watch…

HOW CAN THEY POSSIBLY CHANGE COLOUR SO QUICKLY?

Scientists are still puzzling this out. In a conch shell, it seems the flounder can coordinate its amazing all-round vision with its hormones, instantly releasing certain pigments to its skin cells and suppressing other pigments to make the colour match. Not convinced? Then watch this short video and prepare to be impressed.

Fred Riger of Grand Bahama Scuba, who kindly keeps a benign eye on my reef fish posts (he’s the expert), adds a third excellent reason for coloration changes: sex… “the male peacock flounder can, and does greatly intensify his colors, presumably to declare territory and attract females to his person. When doing this the males will also signal with the left pectoral fin, sticking it straight up and waving it around.” Maybe that is what is going on in the photo below – intensified, non-camouflage colours, and a raised fin…

Peacock Flounder on a plate – Kim Rody Art

Credits: Melinda Riger of Grand Bahama Scuba for almost all photos; wiki for 2 illustrative images

NASSAU GROUPER: VULNERABLE, ENDANGERED… & NOW PROTECTED

The Nassau grouper Epinephelus striatus is one of a number of Caribbean grouper species found generally in the Northern Bahamas and specifically in Abaco waters. Others include the Black, Tiger, and Yellowfin groupers, the Red Hind,and the Graysby. The Nassau grouper is special, however, not least because (unlike the others) it is on theIUCN Red Listas an Endangered Species and is also a USNational Marine Fisheries ServiceSpecies of Concern. It is considered the most important of the groupers for commercial fishing in the Caribbean, and the IUCN listing data suggests that a population decline of 60% occurred over the last three generations (27-30 years), a startling rate. The current population size is estimated at >10,000 mature individuals.

The Nassau Grouper is a creature of the coral reefs in the Caribbean and adjacent seas, though it can also be found in deep water. It feeds in the daytime on small fish and small crustaceans such as shrimps, crabs and lobsters. It lurks in caves and recesses in the reef, sucking in the prey that passes unsuspecting by. The coloration of an individual fish may vary considerably with conditions, and it can adapt its colour to its surroundings as camouflage.

Tiger grouper meets Nassau grouper

Spawning takes place in December and January as the seawater cools, always at full moon, and always in the same place. In the moonlight, huge numbers of the grouper gather together to mate in a mass spawning aggregation. This may continue for several days. However, the species is slow breeder, which is why overfishing is particularly damaging to the population as the depleted stock cannot readily be replaced.

CONSERVATION ISSUES

There are other besides factors commercial overfishing that make the Nassau grouper so vulnerable, including fishing during the breeding season; taking undersized fish; pollution and reef decline; habitat loss; and invasive species. The spawning areas are especially vulnerable to exploitation. In the Bahamas, as elsewhere, the government has now instituted a closed fishing season for the Nassau grouper. Here is the BREEF flyer, just circulated – and in fact the reason for this post, which reminded me that I had planned to write about this fish!

Nassau grouper is eaten by barracudas, lizard fish, dolphins, sharks and other large predators of the reef community. But the predators that have the biggest impact on the grouper population are humans. People are fishing groupers before they can grow to maturity and reproduce. Sex change may also cause a problem. In undisturbed areas there are usually equal numbers of male and females. In heavily fished areas there are often three or more times more females than males. This means many eggs will not be fertilized during spawning. Other threats include, habitat destruction, coral breakage from divers, siltation from construction, runoff from logging and agriculture, dredging, sewage, oil spills and other contaminants that harm coral reefs where Nassau Groupers live.

There’s an extent to which a country can be judged on its attitude to wildlife from the stamps it chooses to issue. It’s something to do with appreciation and promotion of the country’s natural resources. For example, North Korea rates nil in this respect, with stamps involving scary weaponry, flags, marching and eerily glowing leaders – not a single sparrow to be seen. By fortunate contrast the Bahamas and itsPostal Service score very highly in celebrating the diversity of the wildlife of the islands.The Nassau Grouper was first featured on Bahamas stamps as long ago as 1971, some 25 years before the IUCN Red Listing, and probably before the sharp decline in population numbers had even begun.

In 2012 the Bahamas Postal Service released ‘a new definitive 16 stamp series’ depicting the marine life of The Bahamas. The Nassau has been promoted from 5c in 1971 to 70c in 2012. That’s inflation for you.

Finally in 2013 BREEF’s 20 years of marine conservation was commemorated with a distinguished and colourful set of 8 stamps, noting in their release:‘Two of the new stamps feature the Nassau Grouper, a now endangered species that has experienced severe population decline throughout the region… BREEF is well known as an advocate for an annual closed season for the iconic Nassau Grouper during its winter breeding period. The push for the closed season was based on scientific evidence of population collapses throughout the region due to overfishing. BREEF is calling on the government to implement a fixed closed season for the Nassau Grouper in order to protect the species and the fishing industry. The closed season traditionally runs during the spawning season from December 1st until February 28th, to allow the fish to reproduce. BREEF is calling urgently for the announcement of this year’s Nassau Grouper closed season….’ And so it came to pass… Not only is the Nassau grouper now worth 2 x 65c; it is strictly protected for 3 months during its breeding season. Maybe philately even had a hand in getting somewhere…

‘WTF?’ IN BAHAMAS WATERS (3): LETTUCE SEA SLUG

The ‘WTF’ series so far has covered Bahamas reef fish on the bizarre end of the unusual-to-completely-weird appearance spectrum. And it has stood, of course, for ‘What’s That Fish?’. Today, it doesn’t. The feature creature isn’t a fish at all; it looks like a plant; it is in fact a SACOGLOSSAN - specifically the Lettuce Sea Slug Elysia crispata.

The head end is on the left…

The name ‘sacoglossan’ literally means ‘sap-sucker’ (the sapsucker bird has a different latin name, however). And the slug’s frilly edges supposedly resemble certain types of curly lettuce. I’ve no idea where the ‘crispata’ comes from, but I am sure it doesn’t relate to crisp lettuce. These are creatures of shallow, clear waters such as the sub-tropical reefs of the Bahamas.

‘SOLAR POWERED SLUGS’

This isn’t a technical forum and too much science hurts my head. This species primarily lives off algae. However I give you the word KLEPTOPLASTY to drop into your conversation. In a sentence, algae is eaten but only partially digested; certain elements are stored to produce photosynthesis by which light is converted to energy and the slug can live without food. But baffle your neighbour at dinner, why not, by summarising the process as “chloroplast symbiosis”. Meanwhile, I’m fetching a beer.

My research suggests that very little is known about the mating behaviour of these slugs. The pair shown below may be exploring the possibilities, or at least trying to work out which end is which. One is easy to tell, but the other? Time to make our excuses and leave…

HOW FAST, EXACTLY, DOES A LETTUCE SEA SLUG MOVE?

This rather beautiful video from ‘CORAL MORPHOLOGIC’ will reveal all. You’ll soon see that progress is very slow. I recommend watching the first 30 seconds and you’ll get the idea. If you choose to persist, you will see the slug sort of turn a corner to the left.

WTF? (WHAT’S THAT FISH?) 2: STRANGE BAHAMAS REEF FISH

WTF 1 concerned the REMORA, the upside-down looking fish with the trainer-sole sucker on its head with which it attaches itself to sharks and other large undersea creatures. If you’ve ever seen a picture of a shark with one or more grey passengers hitching a ride, those are these.

WTF 2 features some creatures found in the reef waters of the Bahamas that make you wonder just how and why they are as they are. They look unnecessarily complicated, and the design is somewhat outlandish. See what you think of these…

BURRFISH

SLIPPER LOBSTER

SCORPIONFISH (& header image) camouflaged against coral

COWFISH

TRUNKFISH

PORCUPINE FISH

“Watch this…”

“Ta Daaaaaa”

AIRPLANEFISH*

*Well, it’s really airplane wreckage. Besides a few other planes and a variety of ships that can be explored underwater, there are also two locomotives in Abaco waters that “fell off” a ship while being transported. Now recreate in your mind the subsequent conversation with an insurance company…

SHELL HOMES: HERMIT CRABS IN THE BAHAMAS

I’m feeling distinctly crabby right now. In a skilled move that would impress the Bahamas utility providers, the UK’s very own much-vaunted BT selected us for the privilege of being unplugged from the grid last week. From the time of reporting the problem, it has taken them 6 days to plug us back in. It’s a little reminder of the far more persistent Abaco experience! No landline, no wifi, no email for almost a week. To begin with, it was a light relief. After nearly a week, not funny anymore. Here are some nice crabs in conchs to celebrate getting back online while reflecting my crabby mood.Find out more about Hermit Crabs – in particular crab racing at Delphi and the intricate rules – here:WACKY RACES AT DELPHI

‘TREAT WITH PATIENCE…’ – NURSE SHARKS IN THE BAHAMAS

The scientific name for the nurse shark sounds like something Bilbo Baggins might have said to summon elves to his rescue: Ginglymostoma cirratum. Actually the name is a mix of Greek and Latin and means “curled, hinged mouth” to describe this shark’s somewhat puckered appearance. The origin of the name “nurse shark” is unclear. It may come from the sucking sound they make when hunting for prey in the sand, which vaguely resembles that of a nursing baby. Or it may derive from an archaic word, nusse, meaning cat shark. The most likely theory though is that the name comes from the Old English word for sea-floor shark: hurse.

Nurse sharks are slow-moving bottom-dwellers and are, for the most part, harmless to humans. However, they can be huge—up to 14 feet (4.3 meters)—and have very strong jaws filled with thousands of tiny, serrated teeth, and will bite defensively if stepped on or bothered by divers who assume they’re docile.[There are recorded instances of injuries caused to divers who have tried to pull nurse sharks by the tail. And serve them right, I say. Treat them with patience – and respect!]

Notice that the nurse shark in the above photo, and in the header image, is being attended by REMORAS. Click the link to find out more about the strange relationship these ‘weird suckers’ have with larger marine creatures.

They use their strong jaws to crush and eat shellfish and even coral, but prefer to dine on fish, shrimp, and squid. [And also stingrays, apparently. They have been observed resting on the bottom with their bodies supported on their fins, possibly providing a false shelter for crustaceans which they then ambush and eat.] They are gray-brown and have distinctive tail fins that can be up to one-fourth their total length. Unlike most other sharks, nurses are smooth to the touch.

Nurse sharks are found in the warm, shallow waters of the western Atlantic and eastern Pacific oceans. They are abundant throughout their range and have no special conservation status, although the closeness of their habit to human activities is putting pressure on the species.

Nurse sharks are nocturnal and will often rest on the sea floor during the day in groups of up to 40 sharks, sometimes piled on top of each other.

FAST FACTS

Type: Fish

Diet: Carnivore

Size: 7.5 to 9.75 ft (2.2 to 3 m)

Weight: 200 to 330 lbs (90 to 150 kg)

Size relative to a 6-ft (2-m) man:

Credits: All photos Melinda Riger, Grand Bahama Scuba; range map and text mostly NATIONAL GEOGRAPHIC filled out with other pickings